Wow you really doubled down on this. The main reason she started to fall in love was because he put others before himself, saved her and her sister's secret from the whole island nation, and is a willing enemy to the World Government. The seduction test was just her desperate attempt to find any fault in Luffy since her beauty and attractiveness was her main defense mechanism. Luffy beating that defense mechanism is what allowed her to admit to herself she likes him. Treating her as a normal person instead of "The most beautiful woman in the world", a Warlord, or a former Celestial Dragon's slave was the last act she needed to let herself fall in love.
Read the media you're consuming properly and do not take everything in face value especially in One Piece. She likes Luffy DESPITE ignoring her, not because he's ignoring her. Her falling in love, however goofy bordering creepy it is, meant a lot as a statement due to her trauma and her current outlook in life. It's not just because some surface-level reason as "women only care about men who don't give a sh** about them" you and the other person think it is.
You almost got it right with these sentences. "She didnt fall inlove because he did heroic feats. He is not a horndog and interacted with Hancock just like how he handled other ladies." I'm just confused as to why you thought the MAIN reason of her liking Luffy was that shallow for a character as complex as Boa Hancock.