You’re on the wrong mountain and needs to get to the other side. Here’s the, somewhat farfetched, way:
Take the WEEDS from the mountain and walk to the right. On the gound here are a piece of FLINT and a lot of rocks. Take the rock, actually, take the exploding BUGS underneath. Then enter the cave. Take the ROPE and take the BONE standing against the wall. Also look in the boneshards next to the skelleton. There’s a OBSIDIAN in it. Leave the cave again. Now we also would like the mallet but it’s guarded by a bunch of bees.
Put the weed on the ground under the beehive. Use the flint on the weed to light it, causing a lot of smoke and the bees will leave. You now can take the MALLET. Now that you have all items, it’s time to make our contraption. Walk back to the left to the cliff.
Use the obsidian with the bone to sharpen one side, making it into a speer. Use the rope on the bone. Use the bone and rope on the branch that grows out of the mountain. Now that the rope and arrow are ready, we must find a way to get them to the other mountain.
Use the bugs on the rope to get an explosive device. Finally use the hammer on the bugs to rocket the arrow to the other mountain, making it possible for you to slide to the other side.
Watch where you land though…
Game source: A copy of the game was found here on the internet.