Welcome
Arfus!
I totally agree with Fewormany too.
In fact, I think the strap makes the jacket extra cool, like F says it's one of the defining features of that style of motorcycle jacket, and I like the nonchalance of the strap when it's worn open.
I agree too that pretty much anything goes with your jeans and shoes.
Maybe you usually do this anyway, but for another idea, you can experiment if you like with tucking your shirt in and wearing a nice belt too.
There is an art of tucking in, ranging from the ridiculous to the flattering and discreetly stylish all the way to the embarrassingly pretentious, so like Fewormany says you can look at photos of what you like and play around with that too. Ditto for sleeve rolling. I think the shirt fits you well.
Have fun!!!!!