The 1948 war was started by Arabs who rejected the partition plan. Israel won that. Vae victis, don’t start wars if you’re not prepared to deal with the consequences.
You’re right that Israel has been stealing land - in the West Bank, via illegal settlements. They should withdraw those settlers, but it is irrelevant to the issue of Hamas because the last settlements in Gaza were demolished in 2005.
I’m not pro Israel. What I am is someone who is anti Hamas, and I’m not going to pretend that the Israelis are chuckling monsters who enjoy murdering babies for the fun of it.