Any given wish in Genshin Impact has about a 0.6% chance of resulting in a 5 star character, but event wishes have a special 50/50 “pity” rate of guaranteeing the advertised 5 star character or weapon at least once every other 5 star on said banner. That being said, all of of characters and weapons on the permanent banner are also available on the event banners, they just have a lower chance of being pulled as a result of the above mentioned 50/50 pity. The rate of any given wish on an permanent banner wish being a Jean is roughly 0.1% while on the event banner is roughly 0.05% until you get a non-advertised 5 star and 0% once you do until you get the advertised 5 star. As such, if you’re goal is to get Jean, you would want to stick with the permanent banner instead.
That said, if you’re goal is 5 star characters in general, you’re best choice is to stick with the event character banner since that is the only way to get those event characters and it *still* has a chance of getting the permanent characters (like Jean). For example, I failed my 50/50 while on the Venti re-run banner in April and got a Diluc, which resulted in a significantly higher chance of receiving Eula the following month.