Remember, Joshua didn’t raise anyone up to be head of Israel, instead they inquired of God, for a little bit.
FOR US, WE SHOULD BE CONSULTING WITH GOD ON WHAT WE SHOULD DO.
Now, the Israelites are in the promised land, but there were still some Canaanites in the land.
If they were not to drive out the Canaanites from their land, the Israelites would definitely fall away and start worshipping the canaanites gods.
Judah and Simeon made a covenant to fight together against the canaanites!