The Palestinians left their homes because they were warned Israel would be attacked when it was formed. They expected it to be a very short war.

It was indeed a short war, as were the several that followed it. Israel kept winning the wars where Israel was very much not the aggressor.

Israel unilaterally withdrew from Gaza in 2005. Gaza then elected Hamas as their government and their official policy has been “Death to Israel” since then.

Hence, Israel’s policy is “We put up a wall and won’t let munitions in. We won’t give you any more cement either because you used the last batch to build tunnels and kill us.”

They are also increasingly less interested in the opinions of other countries and people such as yourself who seem to not care when Israelis are killed.