Lpinkmountain has given you a bunch of good suggestions, (& probably Eric also, though I didn't follow his links.) I have several additions of native trees, most of which I grow. Oxydendron arboreum would probably stay within your size requirements. Acer pensylvanicum tops out at about 35', has green and white striped bark, decorative dangling clusters of spring flowers (tho small and green) and yellow fall color and is a woodland native. Several native viburnums are small to medium, multistemmed trees: V. lantana, V. cassinoides &/or nudum (taxonomy is up in the air), V. prunifolium. all have white spring flowers in flat panicles, late summer to fall berries, and good fall color. Prunus americana, flowering plum, is a small native spring flowering tree with pink to white blooms. I don't know if it meets your requirement of long-lived, but the ones I know have been around 20+ years and are still plugging away. I didn't find any reference to how long they typically live. I don't know if you want to consider them as well, but there are some native large shrubs that include Clethra alnifolia (likes wetlands, has white to pink late summer flowers and golden fall foliage), Fothergilla major (white spring flowers and red to orange fall color), several of the native deciduous rhododendrons, rhus typhina (staghorn sumac, which suckers, but has the most gorgeous fall colors of any plant I know), Ilex verticillata (deciduous, nonprickly winter berry holly), and high bush blueberries. One additional note: I have Cornus alternifolia growing in full sun and full shade and every light level in between, and it's truly a four season tree: creamy white panicles of spring flowers, late summer berries (dark blue with bright red stems) and nice overall shape, peachy fall foliage, and great winter branch structure. It's fuller in sun than in shade, had more blooms, and is nicer foliage color.

Carolina Cherry Laurel. Here is a link that might be useful: Prunus caroliniana

You can also see the opposite branching arrangement in the first picture. Agree that it is some sort of native viburnum. Could also be Viburnum rufidulum, but V. prunifolium has more range in Ohio overall as does Viburnum lentago.

Fringe tree came up twice -- do folks think it's better than the choices I name, or just another thing to consider? To be clear, I'm ok with a tree reaching 30-40 ft in both height and spread, which would take quite some time for both a dogwood and a redbud, no? cearbhaill, I'm not limiting choices to deciduous, it's just that this is a spot not often seen during winter from inside or outside the house, so winter interest is not a primary factor. I'd definitely consider evergreens with good spring/ summer/ fall interest. The holly may be a good choice, too.