"Harry always treated her insensitively even after he realized that she had a crush on him."
How do you know he's not just a mature kind of guy?
Please tell me you meant immature and how do you know he is?
"...but when she first meets just Harry; she didn’t show any attention towards him, only after he was identified as Harry Potter."
And how do you know that that just means that Ginny isn't a shallow person? If she met a wonderful, perfect person who didn't look as great as his personality, she would probably like him. So she didn't recognise Harry as her crush the first second she saw him because she doesn't judge by looks.
You just contradicted yourself, dude. She never knew his personality. She only knew him because of what he did when he was a baby.
"If Harry was interested in Ginny, why would he forget what happened to her in her first year, especially when he saved her?"
Well, let's consider. He just yelled at his best friends, scaring them almost into tears. He's got quite a lot on his mind, don't you think??? He probably wouldn't remember that someone in the same room had gone through the same thing; he was hot-headed, to put it simply.
That’s a whole lot of shit to forget even for a, simply put, hot tempered kid.
"...J.K. can’t just drop the whole crush thing, so she develops it more and that way she can introduce more of Ginny’s character and bring her into light."
If this is true, then how did she just "drop it" during OotP? Ginny completely forgot about Harry in fifth year. Maybe the crush was still developing all through fourth year, because Ginny does like him (not because JK couldn't "drop it"😉, and the forgetting part was just an act.
Maybe she completely forgot about him because she realized that she had no chance with Harry fancying Cho.
Here’s an exert from the Order of the Phoenix book:
"But," said Ron, following Hermione along a row of quills in copper pots, "I thought Ginny fancied Harry!" Hermione looked at him rather pityingly and shook her head. "Ginny used to fancy Harry, but she gave up on him months ago. Not that she doesn't like you, of course," she added kindly to Harry while she examined a long, black-and-gold quill. Harry, whose mind was still full of Cho's parting wave, did not find this subject quite as interesting as Ron, who was positively quivering with indignation, but it did bring something home to him that until now he had not really registered. "So that's why she talks now?" he asked Hermione. "She never used to talk in front of me." "Exactly," said Hermione.
"As for Ginny, I think she’s going to end up with Neville."
Again, Ginny is a growing woman, she knows what she wants, and it's not Neville. She said herself, the only reason she went with him to the Yule Ball was because she couldn't get in any other way.
Oh! That reminds me. When Ron suggested for himself to go with Hermione, and Harry to go with Ginny, neither Harry nor Ginny had anything bad to say about it. Harry simply stayed quiet during the whole thing, and Ginny went scarlet, proving that she probably did still have feelings for him at the time.
I'm not saying she likes Neville now, but she could later on. I agree Ginny still had her crush on Harry, but Harry didn’t say anything because he was distracted when Parvati and Lavender entered the room. It says in the book, “The time had come for drastic action,” so it’s possible he didn’t care who he went with as long as it was with someone.