It's pretty easy to explain: It's complicated.
Basically, it's a conflict that had been running for a really long time.
Before WW1, the area of Israel/Palestine was inhabited by Arabs and controlled by the Ottomans.
During WW1, the Brits promised the Arabs that they'd back an independent arab state there, if the Arabs revolted and successfully kicked out the Ottomans.
The Arabs did their part, so Britain, being as trustworthy as ever, turned around and divvied the Ottoman empire up between them, and Britain got control over what was then called Mandatory Palestine, which the Arabs saw as a betrayal. The official plan was for the Brits to rule the Mandate "until such time as they are able to stand alone".
At the same time, the Zionist Jews wanted to have a national state, where they could live without persecution, and many European nations, where antisemitism was rampant, wanted them gone from Europe, so they kinda had an agreement there. The original plan was to move them to a part of Uganda, but that fell through so Palestine was chosen.
Already long before the national state was created, lots of Jews moved there and created settlements. The Arabs there weren't exactly happy about that massive influx of settlers and the Jews also weren't happy about the natives. Each of them started an uprising over the following years, and with tensions rising, the UN drafted a partition plan.
While the opinion of the Jews over that partition plan was ambivalent, though leaning towards being happy about it, the Arabs were decidedly unhappy about it. They thought, that the UN was overstepping it's rights and that the partition plan was violating the principles of self-determinism set forth by the UN charter.
So a war broke out between the Arabs (including surrounding arab countries) and the Jews there, which resulted in a victory for the Jews. After that, the area was divided up between Jewish Israel, the west bank area controlled by Jordan and inhabited by Arabs, and the tiny area called Gaza strip, controlled by Egypt and inhabited by Palestinians.
The area the Palestinians received after the war was significantly smaller than what was outlined in the UN partition plan.
In 1967, during the six-day war, Israel captured the Gaza strip and it's been under Israeli occupation ever since. In 1993, Israel granted the Gaza strip limited self-government over the area. Basically, Gaza was allowed to self-government about matters of the populated areas, but Israel remained in control in regards to the airspace, the territorial waters and all border crossings except the one towards Egypt, which is controlled by Egypt.
In 2007, Hamas took over the government of Gaza. Most of the world classify them as a terror organisation, and they have been e.g. shooting home-build missiles into Israel and also have mounted a few small-scale insurrections and attacks against Israel.
Israel on the other hand has been casually bombarding and killing Palestinians for a very long time. Also, they let Israeli settlers illegally settle in occupied Palestinian territories, which the Palestinians are not so happy about.
From 2008 until 2020, roughly 5600 Palestinians and 250 Israelis (including many civilians on both sides) have been killed, and 115 000 Pakistanis and 5600 Israelis have been injured (source: https://www.statista.com/chart/amp/16516/israeli-palestinian-casualties-by-in-gaza-and-the-west-bank/).
The Gaza strip is pretty much an outdoor prison, with a massive population density, low life expectency and abysmal living standards. People are generally not allowed to leave from there. Israel routinely cuts water/electricity, which are both supplied by Israel in response to attacks from Palestine.
All in all, it's a right mess that's been brewing for over 100 years, with no easy solutions. By now, everyone who has been responsible for causing the original mess is dead. Of the leadership neither side is in the right, both sides are making everything worse. There is no solution in sight.
The Palestinians fight the oppression by killing civilians, the Israelis counter by killing civilians and making life even more hell for the people in the occupied territories, who in turn fight even harder and kill more civilians.
Reducing oppression is hardly possible, since that would allow the Palestinians to mount bigger attacks.
Which brings us to the current situation. Palestinians managed to break out of Gaza, at many places even destroying the perimeter fence. They then invaded some towns and a music festival in the border regions, killing a few hundred Israeli civilians and taking some more hostage. Israel countered by bombarding the Gaza strip, killing a few hundred Palestinian civilians. They also, again, cut power and electricity, and the whole western world then responded with cutting food supply.
This in turn will radicalize the Palestinians even more, who will fight harder, and who knows where it ends. Probably with the Israelis finally finding the same answer to "the Palestinian Question" that Germany found for the "Jewish Question" in the 1940s.