I would say it is load bearing and it looks like a 4x4 instead of a 2x4. Take it out and see what falls down? Frequently, many things won't totally collapse although it could drop the steps by a few inches. Of course, you still have the option of a total collapse. But, I'd guess it's load bearing.
A post on a brick is a fairly standard old style method of holding things up. If there's any possibility of moisture in the brick at the bottom, put a bit of tar paper or metal flashing between the post and the brick. That's what I'd do, anyway.
We bought a fixer upper last year where the previous folks fixing it didn't seem to think that a 1"x 8" T & G wall could possibly be a load bearing wall. After they removed it, the ceiling dropped by about 3". The post under the front corner of the living room (this is Hawaii, a lot of houses live on post and beam) had rotted since they didn't have a moisture barrier at the bottom of the post sitting on a concrete block so the bottom of the post rotted off. That was another 3"+ drop for the front living room corner.
It's 'just' one 4x4 post on a brick. (I do like using a floor jack to jack up floors, that was fun in a strange way.)
Simpson stand off post base and there was some more Simpson fittings added, but the 4x4 post braced both ways with a 2x4 was a pretty standard post construction method for decades. At least, in Hawaii, it may be different in your location.
If you're worried about your post being knocked off the brick, you could replace the brick with a new longer post and a Simpson base.