Mulch 3” over the roots and plant outside the immediate root zone. No mulch volcanoes or worse raised beds that kill the roots. In my area you can plant a ground cover like asiatic jasmine that will cover the roots and stay green

Plant a low groundcover around the tree--we don't know your zone but perhaps Geranium maccrorrhizum, Liriope (not L. spicata), or one of the spreading Epimediums. It's certainly not a "terrible tree" and it's great the city won't allow it to be cut down.

What is the green thing to the right of the tree?

An arborist can evaluate the health of the tree and also make recommendations about what will not cause more damage.

Plant a ring of some ornamental grasses that will grow no more than 3’ tall. Plant them out from the tree but not quite as far out as that blue utility marker. They might flop a bit but they will blow in the wind and nobody will notice those roots.

I'm not a great fan of hosta, but I have a ring of hosta around an oak tree, where not much else will grow. They will grow big enough to hide the roots (unless you buy a super-dwarf variety). They will probably at least partly cover the green thing.

Some inspro