Challenge 1- Riddle

We don't come alone,
We don't come in a pair
We are a group of identical siblings
In a festival we come,
your happiness we share.

We might be red or yellow or green,
But we all have a single mission.
That is to lighten up everyone's lives.
So dear friend, we assure you,
To your house, we are a beautiful addition.

When in the black wintery nights,
There settles the white and cold snow,
We lighten up your house and the tree
By sharing lights and happiness galore.
Who we are, do you know?

There comes the white bearded man in red,
Carrying packets of happiness.
To welcome him, we are ready,
Brightening up this and that.
Now, Who we are, can you guess?