the floating action I believe is defined by .jwmrc
You can temporarily move this to something like .jwmrc_ob
and make a new one:
https://joewing.net/projects/jwm/config-2.3.html
This is a good guide to what you can and can't do. Notice where it says that if tiling attempt fails it falls back to cascading, so you still have a functional wm while you are editing and reconfiguring/restarting jwm.
I don't use tiling because eye sight requires to have at least 60-70% on one terminal screen so I float and switch windows.
If you look at .config/jwm/keys you can modify this to match your i3 habbits, but why not install i3 as well, they are both very small. Either a dm or through editing .xinitrc you can start one or the other.