Eh, I think it's more related to survivorship bias of the movies we remember. Most movies from decades ago were utter trash then too, we mostly remember the good ones while most of the rubbish fades away and is forgotten.
While it's definitely a partial survivors bias, I can't really name any recent movies that stand out as timeless classics. Avengers Onfinity War/Endgame was a massive point in time, but hardly something to watch endlessly even now. Star Wars is still clinging to movies made nearly 50 years ago. Spider man had a moment being the first post covid movie, but the film isn't memorable. Kingsman has been a great revival of the spy movie genre, but it's not masterpiece level. You could make a case for The Dark Knight, but it's easily just as memorable due to Ledger's death than the film's quality.
They already are, and heavily influenced animation studios everywhere. Even in Japan, the land of god-tier animation, some studios learned a lot from Spiderverse.
I only watched it due to internet hype making me curious enough to check it out. If anyone reading this still hasn't seen it: Just do it. Trust an internet stranger and just jump blindly into it. Do it. You will not regret it.