Most independent sources I’ve seen reporting on numbers have been Palestinians. The UN is not reporting on casualties because it cannot verify any of the claimed numbers.
And Hamas lied about 500 Palestinians being killed in one attack on a hospital by Israel, except it turned out that attack was actually Islamic Jihadists misfiring, and nowhere near 500 people died.
Hamas verifiably made up that 5% of the casualties in this war, so no, you shouldn’t believe the rest of their numbers.
And Hamas has fired thousands of rockets into Israeli territory since Oct. 7th, that goes beyond defending yourself in a hospital.
And the bombing and siege warfare started after Hamas invaded Israel, killed over a thousand civilians, and fired thousands of rockets at Israeli cities.