Having its root flare exposed (the junction where roots branch off of the trunk base, as pictured here) is exactly how trees should be growing, so this is a benefit, not a problem. Too many trees are either planted too deeply (the flare is buried under several inches of soil) or mulched too heavily, both of which can negatively impact its long-term health. Some tree species, like maples, can be prone to developing girdling roots if the root flare is hidden or buried, a condition that can lead to trunk and canopy dieback later in life. You can learn more in the page linked above, but the pictures are showing a good exposure of the root flare, so no correction is needed or recommended. Don't cover them up with soil or mulch, though a 2-3-inch deep flat layer of mulch used around other areas of the root zone (where lawn is struggling due to the shade and root competition) is fine and can benefit tree health.

If a tree is in decline or has concerning symptoms, have it evaluated by a certified arborist, such as a consulting arborist. They cannot cure or treat every condition, especially if something has been causing canopy dieback for several years, but they can help make a diagnosis and look for sources of tree stress that might be able to be alleviated. Some tree species (for example, birch, though that's not the particular species pictured) are notorious for shedding small dead branches naturally throughout the course of the year.

The fallen autumn leaves in the photos are hard to identify since they're shriveling, but the seeds on the ground look like those of Tulip Poplar (Liriodendron tulipifera). That species thrives in moist soils, and is currently stressed by the drought conditions of the past two months or so; many of them have been shedding leaves early this season as a result.

Miri