“ The “had” — “has” — “have” thing” is called Conjugation, and most languages have something similar
I have ……..We have
You have….You have
He has…….They have
is present tense. In latin there would be 6 different words!
French is (I think) J’ai, nous avons, vous avez, Vous avez, il a, qu’ils ont.
In the past tense all 6 conjugations are “Had” in English, and in future tense all use the phrase “Will have”. Beats me why we don’t say “He have”, but it would sound wrong to me! I think your English is fine, by the way, far better than my Russian!