Is flight actually possible without technology?

That depends upon your definition of "Flight".
Someone could jump off of a very tall mountain cliff and remain airborn for a few seconds. They could use their arms and legs to slightly alter their speed and direction while they were airborn.

Since "Technology" would include such things as paper, metal, sharp sticks, large wooden paddles to flap really hard on your way down, or any type of tool or item created with a tool... You couldn't get much more than that.

Realistically, it would probably require some sort of technology to get to the top of a huge mountain alive. Some type of clothing or shoes, at least.