Qualifying apartheid and sadist acts as human nature or that solving problems is too tough to bother trying sounds pretty weak. These are positions guilty people take to excuse bad behavior.
That imbalance is a prime example why so much of the world believes the current situation, or even just comments to equivalent effect by senior Israeli leaders, is apartheid. If most of the world believes the current situation to be apartheid then its no stretch of the imagination to condemn words or action to remove, destabilize, or eradicate Palestinian prosperity as potential acts of genocide. The same qualifiers and equivocations were used by the aggressors to qualify genocidal acts that occurred in the Balkans in the '90s.
If Israel and Hamas leaders really wanted greater security then they would have already solved for these imbalances. Security is not the primary motivation though, domination is.
In which borders would this demilitarised state exist?
This is more or less what Biden is currently trying to do. The Israelis aren't interested.