Anyways, as mentioned above by OmegaStarScream and PawGo, any address can be used for receiving bitcoin numerous times. So, you can give a single address to as many people as you want. All of them will be able to send bitcoin to you.
However it's possible to re-use an address, due to privacy reasons, that's not recommended to do so.
Note that all bitcoin transactions are public and anyone who knows your bitcoin address can easily check your previous transactions and know how much bitcoin you have.
If you want to protect your privacy, I recommend you to use a HD wallet instead of using a single address and a single private key.
In a HD wallet, you have numerous addresses derived from a seed and you can use a new address whenever someone is supposed to send bitcoin to you.
I was able to understand and picture it well on how it works now. Thanks for the explanation, I now get everything now.