That camera will be a nice way to get into DSLR photography. The kit lenses will be great for daylight. If the sports are indoors or at night the kit lenses may be a little slow. Not that you can't make that work but it will be a challenge.
For my first DSLR I bought a rebel body and a sigma f2.8 lens. This lens was not as good as the top of the line canon lenses but better than the kit. It wasn't the rock bottom price either. I paid about $150(as I recall) more than the kit that was available at sams club but got a solid combo of body and walk around lens.
I'm not saying that is what you should do. I am just offering that as food for thought.
Sigma 70-200. F2.8 would be a good lense for low light,it runs $1249 and has image stabilization or OS same thing.i have a older one that does not have IS but still does good.Tamron has one with out IS for $749 I think.
If you have a lens that is f2.8 and as IS (OS) then you can get nice sharp images in low light. As Scott has mentioned, this is going to be more expensive. If I were going to spend 1200 I would buy a canon L series 70-200 F2.8 without IS (used).
The lens you buy is way more important than the camera body. ANY canon DSLR can make really good photos with a good lens. I buy all of my stuff lightly used. Like a car, let someone else pay full retail and you can get a lot more at the depreciated value. Just make sure you buy from a reputable source if you do this.
Like BERN was saying the lens is most important.i myself buy a lot of used lenses.you can save a lot of money but if you are new a would find some one who could check the lens for you.if you buy from B&H or Adorama used you will be ok they check them before they sale.
I have started renting lenses to try them out before I lay down $800-$2500 for one. I have a good friend that owns a 70-200 f2.8 with IS. They just dropped the price of those to $ 2300. He can practically shoot handheld in the dark with a 7D. I use a 70-200 L f4 without IS on a 7D and. 5DmkII and also get great results. However, I wouldn't do too well with my lens at a Friday night football game.
I think you should rent some lenses and see what is the optimal quality for your budget. There are several places that rent them.
Those are great lenses!
If you have the budget I'd go with the 5D MkIV. It has a great dynamic range with great detail in low light. If you're using Light Room to process the images I've see very good detail brought out of the shadows on images that from earlier cameras couldn't be done.
A 5D MkIV w/ 70-200 2.8 is II combo would be perfect for indoor sports...and everything else for that matter.
I've gotten my last few items refurbished from Canon USA. You can save some $. They have the same warranty and you know it was checked out well. The 5D MkIV is $2799 vs $3099.