possible noob question

[Maximus Heronimus]

Hello all, i'm new at this forum, 

i'm a person with special needs, and a long term linux user

i'm working at my daycare center with Gimp...

and Due Corona i'm at home as a lot of others

now my question
i've gotten into a 3 layers project... 

the goal is getting a giant bunny into a street photo 

so i did manage to cut the streets, and sky... and also get the giant bunny in the picture

i've added the alpha layer, did a search on YT and tried erasing the whole part of the sky and vice versa,

i wanted to be more precise and tried the inteligent scissors and that worked even better, and be able to get both sky and street in new layers
also with inverted mode it was a breeze to get both...
but now the part i'm really struggling with..
i cant get the edges exact due to the sometimes inacurate behavior of the intelligent scissors
so i'm kinda bummed out...

what steps do i have to do to make the whole picture better?

thanks a lot !