In English, you don't refer to any person as "it" unless you want to be rude/insulting.
This sounds correct in English. We have the awkward problem of avaoiding that lengthy phrase "his or her" as an alternative. "The child loves its mother" would be said, suggesting the appropriate gender tacitly. This is acceptable (and economical and thus elegant) English.
It's commonly used in English, at least. Traditional grammar would have you use "his Mother" in that case.
Besides, I am a Spanish person trying to learn German through English hahaha, this stuff drives me crazy
This sentence (Das Kind mag seine Mutter) implies the sex of that particular child, doesn't refer to the gender of the german word "das Kind",
The form for "the child likes her mother" would be "Das Kind mag ihre Mutter" - both ihre and seine are in the feminine as they proceed Mutter but specify the sex of the child.
I'm fairly sure that grammatically the gender isn't "passed" to the child and that grammatically we shouldn't know from this sentence what gender the child has. Seine is the possessive pronoun for both Maskulin and Neutrum. Aber, ich bin noch ein Anfänger!
You're right in noticing that the neuter gender of das Kind is the one to be referred to. It is just that sein also means its, as well as his. That's it.
No, sein is the possessive for his AND its, masculine and neuter. Das Kind is neuter so uses sein as the possessive. Die Mutter is feminine and so we must add an -e to sein hence seine. The reality is that Das Kind mag seine Mutter should not accept The child likes his mother as a valid translation.
Since das can also mean this, can I say "This" child likes his mother."? If not, why's that?
I went for 'the child likes their mother' but this is technically grammatically wrong in English. If you don't know the gender, you put 'his'.
As far as I know, English use IT for things. So the only correct form is 2.