Theory

[BIOShazard]

Ewoks.. they are the little mice of the galaxy. Alone, they are a nuisence. In numbers, they can destroy the best battlion the Empire had. And the only reason 501 beat the jedi was because they took them by surprise.

And 2, Maybe the worlds were all near each other, like Pangaea(the continent that was all 7 put together + subcontinents such as India). So it is possible that Wookies and Ewoks are related, but Ewoks seperated from wookies from Kashyykk onto Endor.

[DSLuke]

it is possible that the Rakata technology which was responsible for the high trees on Kashyyyk also made Ewoks into Wookiees.

[walkerguy]

it is possible that the Rakata technology which was responsible for the high trees on Kashyyyk also made Ewoks into Wookiees.

 

Don't forget Endor also has high trees. Possibly the Rakata took samples from one planet to the other... Wookies being a slave race and Ewoks small little guys perhaps they took ewoks and endor trees from endor and planted them on Kashyyyk which I believe is closer to the core worlds than Endor so that the slave population was much more central. The wookies were then mutated with some sort of gene therapy or genetic reconstruction and used as slaves to construct "wonders" such as the Star Forge.