Before ESB I think the following makes sense:

Clearly the Clone Wars happened in the distant past. Luke is astonished (in the Star Wars novelization) that Kenobi fought in them because “that was so long ago!”. Likely Lucas envisioned The Empire rising afterwards due the devastation of The Clone Wars and general corruption of The Senate that had set in. Like Hitler took advantage of The Great Depression.

It seems likely that Lucas envisioned the Jedi to have extended lifespans (similar to Numenoreans from LOTR).

Kenobi, Anakin and his wife are likely fleeing The Empire when Vader catches up to them - killing Anakin. Kenobi and the pregnant Mrs. Skywalker escape. Maybe they had been part of an earlier insurrection against The Empire before The Rebellion starts.

Obi-wan and Anakin are born OUTSIDE of Republic space on Tatooine - which is why he feels safe to take Luke there to live with his family (Owen Lars and Beru Skywalker - Beru is Anakin’s sister or cousin or…something).

After ESB:

Slight adjustment to canon. Obi-wan takes Luke to live with his brother Owen (ROTJ novelization) on the backwater planet Tatooine (still outside of Imperial territory).

It is possible that Anakin DID NOT START OUT AS THE MAIN JEDI HUNTER. He might have been recruited DURING the Jedi Purge. Maybe he gave into despair (fear) that The Jedi could never be saved and it was better to join The Empire “to restore order to the galaxy” rather than fight against it. So The Empire as an evil Empire could still exist for some time prior to Anakin becoming Vader.

Obi-wan REALLY should have changed his last name though! Unless Kenobi is equivalent to “Smith”.

More Pre-Prequel Info: from Dark Force Rising (June 1992): Jorus C’Baoth becomes “Personal Jedi Advisor” to Senator Palpatine in June of '79 “Pre-Empire Date”. Outbound Flight leaves Yaga Minor on April 1 '64 PED.