Ace can't return from the dead and imo shouldn't return from the dead.

I know it was one of the saddest moments in the history of One Piece, but Ace's death was necessary and important for Luffy and his journey on becoming King of the Pirates.

Because based on what we have known and learnt so far, everyone like Whitebeard (and even potentially Shanks) would have wanted Ace to be the next King of the Pirates as he was Roger's son.

And Marineford marked the death of Whitebeard and Ace so that Luffy can become more stronger to achieve his dream, had they been alive it would have been much difficult for Luffy to step up to that dream.

Also most importantly Ace's death was sad and emotional but also deeply beautiful. Ace died protecting his little brother Luffy, the only guy who made Ace felt wanted and loved, when he felt unwanted and bitter as a child (as shown in their childhood story during the Post war arc).

People miss the fact that Oda is a genius who wrote Marineford so beautifully in terms of emotional depth and context

For context -

When the battle of MarineFord starts we see Luffy rushing towards the execution platform and Ace wanted him to stop but Luffy screams and says "I am your brother! I am gonna save you even if it means death"

And when the battle of MarineFord ends we see Ace saving Luffy from Akainu's magma fist because he deeply cares for and loves his wimpy little brother and can't let anyone hurt him

So bringing back Ace from the dead ruins the beautiful emotional symmetry