Especially AN 1 and SN 43 makes it absolutely clear. Even if you experience a split second amount of time in jhāna, “the time it takes to snap the fingers” as AN says, it’s first jhāna!
It’s the later Theravada scripture that redefines jhāna as a type of formless frozen samadhi.
You can hear in first jhāna, you can think in first jhana, you can walk for alms in first jhana.
