If someone catch a small ball it is easy to catch it. Just open the hand and grab it. Well, if aiming and coordination works as they should.
You can also grab another ball. Just use the other hand and grab it.
Now it becomes more tricky. To catch the third ball you have to let go of the first. Drop it. Once dropped one of your hand is free to catch the third ball. Although one ball is now on the ground.
A better way of catching the third ball (and fourth and...) is to start juggling. While juggling you can catch more balls, keep them in air and hand - and if you are skilled you will drop none. How many you can catch is a matter of your juggling skill.
To make this even better you can now start to collaborate. Use the people around you. Share the balls with them. They have hands and maybe juggling skills too. When juggling skills or hands are depleted - grow the team. As the team grows and collaboration skills increases you can catch and maintain more balls.
And now you can also be part of other people's ball catching games.
Now, lets play with ideas and balls at the same time:
1. First you need to open your hand and mind to be able to catch any ball (or idea)
2. To be able to receive and develop many ideas you need to have at least basic juggling skills. (Yes, keeping two balls without dropping any, counts as basic skills.)
3. But, to be able to really get moving you need to collaborate and share the ideas with other people. That way you can develop all the ideas you find.
4. And now you are part of other people's idea development network.
(Thanks to @redmamba and @KRCraft for making me think.)