The book of Joshua (the text you're primarily referencing) is regarded as a fairly late fiction. The entire account has polemic purpose, though scholars debate exactly what purpose that was. You'll notice it's a very different kind of book from those that precede and follow it in chronological order. (Among other things, it's just not as interesting to read.)

Furthermore, archaeological evidence is that the early Hebrews build new settlements on the less inhabited highlands. There is little evidence they destroyed large cities in the area. The city of Hazor, for instance, is reported destroyed in Joshua, but appears in Judges fully occupied by non-Hebrews powerful enough to oppress the entire land. The city of Jericho was not even occupied at the time of Joshua's conquest. Jerusalem itself is supposedly defeated, but we know from other accounts that it was only taken by the Hebrews centuries later.

All in all, the evidence is that Hebrews settled (or at any rate formed a distinctive culture) in the highlands of Canaan some time a little before the late bronze age collapse. They probably warred with their neighbors as most of these nations did, but they were unlikely to have destroyed many cities, given their poverty, small numbers, lack of technology, and decentralized political structure.

Indeed, this is something like the picture we get in Judges and Samuel, where the Hebrews are always on the back foot against their more powerful neighbors, but gradually form a cohesive national identity and eventually a kingdom capable of defending itself. By the time this kingdom falls to the neo-Babylonians, it has survived centuries and outlasted almost all of the neighboring nations we read about in the earlier Biblical narratives. Little wonder that the people who outlasted their oppressors dreamed of a past when they had actually destroyed them.