Ok... I'm dropping this.
I like isekai and I like lewd. And I don't even mind permavirgin isekai MCs that much, as long as there's something interesting to compensate the blatant shallowness of those characters.
Here, though? Nothing. The premise (humans OP) isn't developed well enough. The story is crap from start to end, with action being boring and predictable to the point of suspension of disbelief. The MC is braindead to the point of being cringe. None of the girls (doormat, bitchy, cute sidekick, "blooming") is developed enough to be likeable. I love boobs but let's get real, here the manga offers nothing but boobs - it's like the author decided to use the worst isekai tropes together, and managed to make them even worse.
I'm going to read a hentai because it has more plot (and boobs) than this crap. 1/10 because I can't rate it lower.