is sub 1:15:00 possible?

Depends on what you define as theoretical limit. If you talk about theoretical human limit then I'd say 1:15 isnt possible. I'm sure a TAS could do it though. Alternatively it could be made possible by finding a way to skip any race/bossfight/area. For example there is a known way to access the entrance to the Dino area boss early, but unfortunately the loadzone is not there before you beat the required tracks.

hol' up can u send or make a vid on, dino island early and ngl this game i very well made for least amount or bugs/game breaking gliches

Yeah I found the dino island bridge thing years ago, but I'm pretty certain that there's no way to trigger the bossrace without completing all other races first sadly.