I've done a bit of googling and found these songs that have the same chord progression in the same key (not necessarily the same feel*) as Let's Get It On and Thinking Out Loud. I'm not saying anyone's ripped anyone else off, just thought it was interesting. Like I said, it's a common chord sequence.

Ricky van Shelton - It Wouldn't Kill Me
https://www.youtube.com/watch?v=8N_4-cma8n0

Third Time Out - Across The Miles
https://www.youtube.com/watch?v=EzBJOUTiwZs

Kenny Chesney - Touchdown Tennessee
https://www.youtube.com/watch?v=qaHlqq8dvNA

Cowboys seem to love it

Mott The Hoople - No Wheels To Ride
https://www.youtube.com/watch?v=lOdVsLZ4Vlw

Hannah Montana - Rockstar
https://www.youtube.com/watch?v=TVKpG7BkcLY

Yeah, even Hannah Montana is getting involved.

Kip Moore - Girls Like You
https://www.youtube.com/watch?v=o7H-bSlLoqI

The Carpenters - I Won't Last A Day Without You
https://www.youtube.com/watch?v=tt5huMICEwU

That's page 9 of Google, I'm done.


*and certainly not necessarily good