It'd be similar in tone to the Ultimate comics, & would take most its inspiration for story & character designs from there, however it'd also be a lot different. Season 1 would begin 2 years into Peter's tenure as Spider-Man, with him already being well-established & already having encountered some of his best-known villains. Peter would be a college student working as a photographer for the Daily Bugle & his girlfriend would be Gwen Stacy.

The season's main conflict would involve J. Jonah Jameson hiring a private investigator to infiltrate Peter and find out how he gets such high-quality photos of Spider-Man, Jonah pays him to be part of an experiment at OsCorp, which ends with him being fused with scorpion DNA, becoming an insane human/scorpion hybrid. The Scorpion goes on a bloodthirsty rampage, with his main motive being to eliminate both Jonah and Spider-Man, & thus the Scorpion would be the main antagonist of the season.

Season 2 would pick up several months later as Norman Osborn (who knows Spider-Man's secret identity) utilizes his "OZ formula" to become the Green Goblin. The Goblin commits several disastrous crimes throughout the city, & both he & Spidey have several confrontations (including one inside the Daily Bugle itself where Peter's identity is revealed to Jonah). In the finale, the Goblin would blow up the Queensboro Bridge, leading to a confrontation between he & Spidey that would end with the deaths of both Norman & Gwen. At Gwen's funeral, Jonah thanks Peter for saving his life against Scorpion & for all he's done as Spider-Man, & agrees not to do a story on Spider-Man's identity.

I don't have much for a season 3, but it'd most likely follow Harry & his transitioning into the Hobgoblin, as well as the formation of the Sinister Six.