If the grade of the surface with the bricks slopes towards the door, there is no band-aid solution. The only solution is to remove the bricks and slope the ground away from the door.

I suppose you could shorten the door and raise the thresh hold, but that creates a trip hazard.

In the winter / spring and when it rains heavily there is a build-up of water/ice near the door to my detached garage. The property slopes down, so I think there are leaks near the door / threshold / concrete foundation. Any advice on how to mend this would be greatly apprecated! I don't want to rip up interlocking brick / landscaping at this time so am mainly looking for band-aid solutions. Thank you!

I’m confused about what exactly it is that you’re asking (especially the part about the leaks—is water getting inside the garage?). Are you trying to repair water damage caused by said-pooling or are you trying to keep the water from pooling there in the first place? If it’s the latter, and a band-aid is what you’re looking for, I suggest sandbags.

P.S. Can we see more of that trompe l’oeil? Who painted it? It’s pretty cool!

What Mac said, and if you don't remediate it, it will likely cause issues with that concrete with freeze/thaw, as well as the door sill. I know you said you don't want to disturb the block work, but I don't see a way around it. If you can't regrade and have the land slope away, I think you'll need to put in some sort of drain system with a sump pump, or a french drain. A photo from further away so we can see the entire lay of the land would help.

Ditto HandyMac. Homes are not submarines. They are made to shed water falling from the sky & slow down low pressure air infiltration. Code requires the surface slope away from the home. A band aid would be to install a drain outside the lowest corner of the door.