Trying to configure STP on a small network with central firewall.

I am trying to configure the switches on a network to use STP or RSTP but I'm confused about how to do this. The network consists of 3 switches, all on the default subnet, so a fairly simple setup. However, all three switches are connected directly to a Meraki firewall. My concerns are as follows:

It seems like in this setup there would be no STP root, unless the meraki can act as root.

It seems like this network has no redundancy. Does this mean I should forgo the use of STP entirely? Should I add redundancy?

And finally would it be considered better practice to connect only one switch to the firewall and connect the other two switches to that one, making it the root?