i want to know iruma’s origin not ameris

That was the first chapter?? His parents gave him to a demon to fulfill a wish or something and iruma has a hard time saying no so we went with it

What if they're not actually his parents
Σ( ￣□￣||)

and what if he’s adopted? and the story is implying that he has connection to the previous demon lord and if he really has then i want to know what kind of connection is that. right?

I think they mean the strange relationship Iruma holds with Derkila and all that drama, not his useless human parents. That's to say if they were his biological parents for real or not I suppose we'll see one day with how much drama is going on in the netherworld at present.