A general principle is to play urgent moves before big moves. The white group on the top left doesn’t have two eyes, so Black can attack it with profit. Once the attack is finished, Black can take a big point like approach or invade a corner.
Also if Black doesn’t play E6 then White can play D6 which would be annoying.
Anyway it’s not obvious that B7 is less good as E6, it’s an interesting suggestion from AI but you shouldn’t worry too much if you missed it.
B7 is still connecting and leave white with a heavy shape.
Considering black shape if that direction occured to me, i would even play a stronger shape with D6 instead of E6.
Your other propositions seem interesting too, but maybe there is some priority to exploit white weaknesses first. Still no big deal as your corner is well settled
