Of course it was. Kayin was the first murder, and he admitted his sin and was punished for it.
There’s a very good reason that the dor hamabul was wiped out: because they abused each other. The dor haflaga was only dispersed, because though they were evil, they played nicely with one another.
Free choice has always been.
In fact, have you ever wondered why we don’t have strong nevuah these days? It’s because the yetzor hara for avodah zara was destroyed. Hashem creates and even playing field to allow room for free choice.
Avodah zara was a intense level of connection to idols, whereas nevuah was the intense connection to Hashem. In order to remove the yetzor hara for avodah zara, the level of nevuah had to drop.
If it didn’t we would all run to choose Hashem. That’s the no brainer. Hashem wants us to actively weigh the consequences of our actions and then choose him.