Unless you can construct a quite high concrete wall (which may not even be effective for noise on a hill that rises above it), there is very little you can do for noise.

The sound of a water feature is nice, especially in a semi-enclosed space as your deck appears to be. They have compact and/or splashless versions if your space is tight.

Soft surfaces absorb noise, use lots of throws, pillows, upholstered pieces, carpets, soft woven wall hangings. Every little thing help reduce the echo feeling inside a space.

Cover the ceiling or just the insets in burlap or fabric covered ceiling acoutic panels, or even reed fencing, so the sound doesn't come from above you too.

Background music?

Thank you for the feedback it’s appreciated!

I wonder how long you've lived in this home? In time you should become accustomed to the hum of traffic. Meanwhile there's little you can do besides erecting a sound wall as Lacey suggested which probably isn't feasible.

We’ve bought it five years ago and have been renovating on and off since. We live in montana and have seen a big population increase, the traffic noise has just increased in frequency. We plan to add a small addition and retire here. ❤️