That is incorrect. Israel has not kept troops stationed permanently inside Gaza since 2005. According to both Israel and the UN, Gaza is still occupied territory of Israel.

Gaza is not a country. It is part of Israel.

Gazans are fighting is because they are being slowly (and since 8 October quickly) exterminated by Israel. Prior to the start of the Zionist movement in Palestine about 100 years ago their was relative peace between all the groups in Palestine - the religious and the non-religious. It is only since the Zionists began their ethnic cleansing that the violence began. The violence began with the Zionists attacking the non-Zionists, not the other way around.