I wanted to post this as a comment first, but maybe it's worth leaving this here - (I'm late to this drama but anyways...)

The final scene between Ji Ling and Lu Wuyi was deliberately left a bit ambiguous so viewers can interpret it in different ways. Some viewers think the final scene shows JL and LWY in the afterlife, so in other words, they both died and meet again in "heaven".
But I wanted to point out below why I personally think that Ji Ling and Lu Wuyi didn't die and actually got a "reset life":

First of all, we know that Ji Ling was successful in "deleting" Lu Wuyi's original Jiu Ying-possessed-version and immediately the world is changed. Wu Shiguang seems to be the only one who actually remembers the previous version of the world (maybe because he was directly next to the tree which was one of the four pillars?). This is a world in which Ji Ling killed Jiu Ying before he could do any big damage and Lu Wuyi's possessed version never existed.
Then we see Li Jie thinking about a voice that he hears telling him "Come and find me". He doesn't know who this voice belongs to.
This is my first argument as to why Ji Ling isn't dead; Why would Ji Ling's spirit tell Li Jie "come and find me" if Ji Ling was dead? This would mean that he is asking Li Jie to die and follow him into the afterlife - something that we know for a fact Ji Ling would never do. He's been praised by all the deities and demons for his kindness. So it would be quite strange for Ji Ling's spirit voice to tell Li Jie to come and find him in the afterlife.
Instead, to me it seems that the writer left it deliberately open if Li Jie would be able to find Ji Ling in this new timeline again. There's a deep connection betwen Li Jie and Ji Ling, so he can feel that Ji Ling exists somewhere out there and this feeling is drawing him towards Ji Ling. To me this seems as a strong indication that Ji Ling isn't dead, that he is alive somewhere and Li Jie can sense that.

Then we have the first moment of the final scene where a little girl is playing and saying "demons (Yaoguai (妖怪) are coming". Ji Ling tells her demons don't exist in this world and they're only made up to scare kids. To me, this phrase from Ji Ling was a way from the writers to show that 1) the group really did succeed in freeing the world of evil demons and 2) Ji Ling is now a human who has no contact whatsoever with any demons or magical beings, so he doesn't even believe they exist.
To me personally, it wouldn't make sense for a little kid who is in the afterlife (=heaven) to be playing that demons are coming. The afterlife is always depicted as a peaceful place after death so it makes no sense that demons would be seen as something fun to play with (the little girl mentions that it would be fun if demons existed). Whereas humans do have this curiosity towards demons, so to me it makes more sense that Ji Ling is in a human world and the sentence from the girl "too bad there are no demons, it's boring without them" is kind of like an inside joke for viewers, because we know the absolute hell Ji Ling went through because of demons, so it's ironic that the little girl says that. It might be "boring" without demons but it's peaceful! And that is Ji Ling's new life now: calm and peaceful.

Then Ji Ling and Lu Wuyi finally meet. Some viewers point to the fact that Ji Ling and Lu Wuyi stand on a bridge as a sign that they went to the afterlife. But I think the bridge was put there deliberately to give this ambiguous meaning.
One reason why I also think the afterlife theory doesn't make as much sense is because usually in dramas when loved ones meet each other or wait for each other by the bridge in the afterlife, they remember each other. In JL and LWY's case they both don't remember each other and are completely unaware of anything that happened between them. In addition, the afterlife scenes in dramas are often shown as a place where the characters used to be at or where they had happy memories. But JL and LWY aren't anywhere where they spent time in their previous life together. They're in a village that doesn't have any correlation to their prior experiences. So to me, the little girl playing with demons, and both of them not remembering each other, are indications that this isn't the afterlife but just a normal, human village.

Also, some fans mentioned that the screenwriter originally planned for Ji Ling to remember LWY, just like Wu Shiguang remembers Wangyan, but then he decided to have Ji Ling also forget his previous life because it would be too cruel. This to me is another indication that the writer's meaning of the final scene wasn't them in the afterlife, because then why would only Ji Ling remember and not both of them?

So all in all, to me it makes the most sense that Ji Ling and Lu Wuyi actually got their wish - which they even talked about during their time together - to live a completely average life as average people together. So after Ji Ling killed Jiu Ying and took Lu Wuyi into the star stone, everyone's fate changed and when they left the star stone and went "back to the future" they both didn't exist in that form anymore because everything changed. But instead of both of them not existing, they've become completely new people living in the human world.
I first thought maybe Ji Ling is now Xizai - Li Jie's younger brother who healed himself after taking dragon blood and who now in this timeline maybe didn't die in the star stone explosion - but that's probably just because I got a bit confused with Ji Ling having the same appearance than Xizai. I actually think both Ji Ling and Lu Wuyi were simply "reset", got new lives and a chance to live as two normal humans who never went through all the trauma of their previous lives. Which is honestly a beautiful ending!