It's fairly evident even from the Spider-Man: Homecoming trailers that, for the second reboot of the Spider-Man cinematic universe, major revisions to the cast were made. This includes Aunt May and Peter, who are (respectively) a few decades and a few years younger than we've typically seen them as well as a more inclusive supporting cast. Another creative revision is the absence of Uncle Ben from Spider-Man: Homecoming; he's nowhere to be found in a very interesting change to what some would consider truly essential Spider-Man backstory.
As Spider-Man: Homecoming director Jon Watts explained recently, by removing Uncle Ben and the emotional stakes of that kind of huge loss the script was able to maintain its lighter feel:
"They talk about that, absolutely. It's not… it’s not a huge thing that I want to go into too much, but there is an acknowledgment that there was a Ben...I mean, we're implying he's dead. We have not at all, again, gone into trying to change his origin story as far as I have been envisioning it. But we, just again, we thought that to keep this fun, light tone, as soon as they have to have their, like, 'Let's remember our dearly departed father figure' — it derails that a little."
As such, Aunt May — who appears to be in her '40s, as opposed to the canonically-correct matronly aunt — is parenting and caring for her nephew Peter all on her own. She and Peter do not appear to be stuck in mourning for Uncle Ben and thus, can keep some forward momentum in their lives.
In the past, Uncle Ben's presence and immediate death provided the emotional stakes for Peter to become Spider-Man. In the Tobey Maguire version, Uncle Ben impressed upon Peter the importance of taking responsibility for one's actions; his death and that reminder of his final lesson turn Peter into a more serious hero. In the Andrew Garfield version, Uncle Ben dies under the same circumstances and, because his relationship to Peter is portrayed as a bit more strained as Peter explores his Spider-Man persona, that death only adds more of a darkness to Peter's character once again.
In the case of Spider-Man: Homecoming, there's still plenty of emotional stakes and weight in the film, it's just coming from a different place. As a reminder, Peter still has to deal with living up to mentor Tony Stark's expectations and saving his friends from his nemesis, Vulture. It's certainly an intriguing revision, but one that will most likely pay off in the long run when it comes to the character development of Peter as yet another Spider-Man reboot gets underway.