Canaan was the grandson of Noah (Noah>Ham>Canaan), and Abraham (a descendant of Shem) was the first to be called a Hebrew, so technically the Canaanites existed before the Hebrews. That doesn't mean the Hebrews were an offshoot of the Canaanites. YHWH existed before the Canaanites or anyone, so whether the Canaanites worshipped a god by that name or not proves nothing.
Biblical archeologist William Denver writes about the consensus in his field being that the Israelites came from the Canaanites.
In this interview he sums it up:
"No Egyptian text mentions the Israelites except the famous inscription of Merneptah dated to about 1206 B.C.E. But those Israelites were in Canaan; they are not in Egypt, and nothing is said about them escaping from Egypt.
Tell us more about the Merneptah inscription. Why is it so famous?
It's the earliest reference we have to the Israelites. The victory stele of Pharaoh Merneptah, the son of Ramesses II, mentions a list of peoples and city-states in Canaan, and among them are the Israelites. And it's interesting that the other entities, the other ethnic groups, are described as nascent states, but the Israelites are described as "a people." They have not yet reached a level of state organization.
So the Egyptians, a little before 1200 B.C.E., know of a group of people somewhere in the central highlands—a loosely affiliated tribal confederation, if you will—called "Israelites." These are our Israelites. So this is a priceless inscription.
Does archeology back up the information in the Merneptah inscription? Is there evidence of the Israelites in the central highlands of Canaan at this time?
We know today, from archeological investigation, that there were more than 300 early villages of the 13th and 12th century in the area. I call these "proto-Israelite" villages.
Forty years ago it would have been impossible to identify the earliest Israelites archeologically. We just didn't have the evidence. And then, in a series of regional surveys, Israeli archeologists in the 1970s began to find small hilltop villages in the central hill country north and south of Jerusalem and in lower Galilee. Now we have almost 300 of them.
The origins of Israel
What have archeologists learned from these settlements about the early Israelites? Are there signs that the Israelites came in conquest, taking over the land from Canaanites?
The settlements were founded not on the ruins of destroyed Canaanite towns but rather on bedrock or on virgin soil. There was no evidence of armed conflict in most of these sites. Archeologists also have discovered that most of the large Canaanite towns that were supposedly destroyed by invading Israelites were either not destroyed at all or destroyed by "Sea People"—Philistines, or others.
So gradually the old conquest model [based on the accounts of Joshua's conquests in the Bible] began to lose favor amongst scholars. Many scholars now think that most of the early Israelites were originally Canaanites, displaced Canaanites, displaced from the lowlands, from the river valleys, displaced geographically and then displaced ideologically.
So what we are dealing with is a movement of peoples but not an invasion of an armed corps from the outside. A social and economic revolution, if you will, rather than a military revolution. And it begins a slow process in which the Israelites distinguish themselves from their Canaanite ancestors, particularly in religion—with a new deity, new religious laws and customs, new ethnic markers, as we would call them today.
Archeology of the Hebrew Bible