This is... tricky. And it very much depends on what you mean by "Canaanites"

So, the Canaanites were a people who spoke a Semitic language and lived in the southern Levant. It's likely that the Hebrew/Jewish culture and religion were offshoots of Canaanite culture and religion.

The Philistines (the people from whom we possibly get the name Palestine) also lived in this general region, and from what we can tell, they were culturally related to, or part of, the greater Canaanite culture as well.

Over time though, as more and more foreign powers occupied the region, the local culture began to assimilate into the cultures of their conquerors. Becoming less and less distinctively "Canaanite" and more Greek, then Roman, and then Arab. The modern, Palestinian, self-identity probably didn't really come about until sometime in either the 19th or 20th century.

So modern Palestinians aren't culturally Canaanite. But what about genetically Canaanite? Once again, it's hard to say, and depends on what you mean by Canaanite.

Genetic studies have shown that most Palestinians are indigenous to the region with large amounts of Arabic genetic admixture. It stands to reason that there would be migration and travel between different parts of the Arab world, so there would some genetic admixture between them. But, there's no historical evidence of any large displacement or extermination of the inhabitants of the Levant after the Arab conquests, so the current population of the region probably have a high degree of genetic continuity with the ancient population.

So, it could be said that modern day Palestinians are genetic descendants of the ancient Canaanites. Of course, so are modern day Israelis. Who, along with having a high degree of genetic descent from the Levant, are still closely genetically related to the Palestinian people. And honestly, human migration has been a constant throughout history. So you can probably find genetic traces of the Canaanites everywhere from Ireland to China.

Most modern ethnic identities were created in the last few hundred years. So, being descended from Canaanites is more of a point of national pride than actual cultural or genetic realities. If the Palestinians want to claim heritage from the Canaanites, they certainly can. They're not more or less valid than any other ethnicity's national origin.

As for your last question "are Israelis truly black?" That's not really the right question. "Black people" is a social construct. A way to divide people into in and out-groups based on their skin color. Sometimes, it becomes a self-identification. But there's no biological determinate over whether or not someone is "black." It's all based how they see themselves and how they are seen by others.

There are some Israelis who have African heritage, and so might consider themselves black. On the by and large though, I'm guessing most don't.

I hope I was able to answer your questions to your satisfaction and that that all made sense.

That's absolutely fascinating, just to consider that the culture that the Hebrews demonized at the time the Bible was written went gave rise to a vast, cosmopolitan culture, which then got crushed by Alexander and Scipio.