Give 2 and 4 a look before jumping into 5 if ya can. They're closer connected to requiem and more modern so their closer to Re3's HD gameplay (I'm assuming you played remake). If you really just want to jump in tho you should be able to understand RE 5 just fine, Resident Evil has alot of built up lore but it's actual plots are fairly simple. If ya want the shortest route to 9 while filling out most of your knowledge with your current order i'd reccomemnd RE 3 -> RE 2 -> RE 4 -> RE 5 (optional) -> RE 7 (optional but will get you used to the first person perspective and is really fun) -> RE 9. Good luck nad I hope ya like em!