I will be using it mainly for photographing my son, his sports and landscapes. My only issue is having to change lens.
That's the point of an interchangeable lens camera -- to change lenses.
Imagine saying, "I want to cook lasagna, soup, steak, lobster, and cheesecake, but I want to stick with just 1 pan and don't want to use any ingredients except eggs."
Sports typically requires a telephoto lens -- like your 55-210. Landscapes require a wide lens usually, like the 16-50. Portraits of your son depend on the portrait length, and how close you want to get to the subject. If you want to photograph him from across the room, you need the 55-210. If he is posing a few feet in front of you, you can take a nice portrait with the 16-50. A tight headshot, would be better accomplished with the 55-210 (or you will need to stand uncomfortably close for the headshot), while a full body shot is better done with the 16-50.
And lots of more particularized lenses serve a variety of purposes.
For me, for landscapes I like my 18-35. For general walk-around purposes, I have a 24-85. For portraits and sports (on full frame), I have my 70-200. For low light or super narrow DOF, I have a 50/1.8. In the past, I've used a 100 macro for real macro shots and as a terrific portrait lens. I switched systems, but I'll be adding such a lens back to my arsenal eventually. For shooting wildlife, I make due with a teleconverter attached to my 70-200, though I may rent a 80-400 for more intense wildlife.
Every camera currently on the market is capable of taking great pics. I dare say they are all basically equally capable. Having the right lens for the right job certainly helps, and knowing how to use the gear helps the most.