You're going to have to provide a geographical location to get any useful suggestions. And give some idea of what you'd like. Trees, shrubs, perennials? Colours? Likes/dislikes? And do want as little maintenance as possible or are you happy to garden?

South eastern Michigan. Medium maintenance
Small tree or shrubs
Nothing to big like the maple was
Love pinks and purples. The peonies that were there are bright pink. Hydrangeas are white. Had some purple gay feather. Deer are a problem. Eat everything. Purple cone flower and lavender in front of deck. Pink rose of Sharon for privacy along lot line. Thank you for your suggestions

Dogwoods are pretty and don't get too big. There should be several that are native to you. You'd probably need to protect them until they get above deer browsing height. I like Cornus Alternifolia

Two tall 4x4 wood posts with metal hooks, 2 more hooks on the house, and attach a fabric solar shade screen to the house and posts. Or 4 posts depending on exact location.

Or build a pergola. Or use umbrellas.

What is that other small tree close to the house? I'd probably remove that. Build in the lower deck to fill that corner. Edge it with large pots like on the other side. Plant in front of that area. A pergola on the new deck section would be nice. Or posts for a sun shade. Or patio furniture like an umbrella table, or an awning rocker bench.

Here are some suggestions:

That looks awesome but I’m not sure what those plats are.
The tree is a cherry. It was really shaded by the big maple. Not sure if it will make a come back