Collision with supposedly aligned box-colliders

Question

I am quite new to game development, and I am trying to create a top-down game with 2D sprites, but with a 3D feel to it. I managed to do so with the 2D engine by setting Transparency Sort Mode to Custom Axis with the axis values set to (X=0,Y=1,Z=0). I then moved the pivot of GameObjects to bottom-center and used the pivot as sorting point for the sprites. I am now trying to create the environment, but my character 'clips' against the Box Colliders, even though I did all I could think of to align them (same pivot coordinates, same collider offset and size). See the attached GIF for an example:

I think that the cause is mentioned here, but there are no solutions mentioned there. My two solutions:

• Remove the colliders, group the objects in a parent object, and add the collider there. But then I would get the same issue if I place two of those instances next to each other.
• I am still pondering to drop this approach altogether and try the same in the 3D engine, but with a fixed camera angle. I lack experience to estimate if that would be a better approach, so if someone thinks that approach would be better suited to this game style, I am happy to hear it.

Can anyone give me advice on this issue, or point me towards resources that might be useful?

Thanks in advance,

Florian

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Some pictures of the settings I used:

Answer 1

DMGregory asked me some other good questions in the comments that made me think about my problem. Based on that, I was able to solve the problem myself. In the end, I solved it by using the proposed CompositeCollider2D, and by toggling Grid Snapping on.

I then aligned the objects while snapping to the grid, and this seems to have resolved the 'clipping'.

However, the clipping now occured at the edge of the wall. In addition, I had to set the BoxCollider2D on the Player, to a CapsuleCollider2D.