Is it possible to connect USB A devices to a 2015 MBP with Thunderbolt 2 ports?

Yes, but not with a simple adapter. You'd need a TB2 dock, and they're pretty much only available used and not cheap, e.g.

https://www.amazon.com/OWC-OWCTB2DOCK12P-Thunderbolt-2-Dock/dp/B00UUCQVBK

You're better off getting a regular USB-A hub and connecting it to your single USB port.

You should have two USB-A ports on a 2015 MacBook Pro both 13" & 15" models. One on each side.

Identify the ports on your Mac - Apple Support

dyuhas Said:

“Is it possible to connect USB A devices to a 2015 MBP with Thunderbolt 2 ports?: My MBP has only one USB port, but it has two Thunderbolt 2 ports. Is there any way to use them to attach USB devices - drives, specifically?”

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Crossover Cable:

Keep in mind, what you are looking for is called a “crossover cable”. So, use those words(perhaps keeping the quotes) when you go about searching for one.