It's okay, as user Handy Corpse pointed out as well below in the comment section I've made use of an asset pack I bought for characters and environment, and in compliance with the jam's rule 'All assets are allowed - as long as you have a license to use it' all other visual and audio assets are sourced: particle effects and post processing shaders are from packs, audio has been sourced from various sources, animations are from Mixamo.com.
Thank you very much for the feedback, I'll definitely expand on the AI if I come back to this project.
As for the blending between characters and environment, I do agree but there is no much I can do to address that feedback I'm afraid, as I am no visual artist and you pointed out I did not make the assets in the first place.
I do disagree however with the feedback about the theme not being present, enemies spawn out of dimensional 'holes' coming out of the ground, and the whole narrative of the game revolves around fighting the invaders coming out of these holes.
I do think it can be unclear how they are there if the player gets to an enemy after their spawn effect is vanished, and I only realised when I was making the video for the game's page that it would be 100x times more clear those are holes if I rotated the round hole to be facing the camera view instead of laying on the ground, like you see in that video.