Questions about openings.

New player here and the amount of openings and their names is overwhelming for me and seeing these I wonder the philosophy behind them.

For example:

Is the decision to play a specific opening purely a matter of preference?

Are Black's openings always based on White's opening?

Are some openings more aggressive than others?

And this last question, the most important for me. If this is ultimately a decision of preference, do you recommend me to look for one that I like and play only that one until I become more familiar with the game?

#1

"New player here and the amount of openings and their names is overwhelming for me"
++ Do not worry about openings, just develop your pieces into play and aim for the center.

"the philosophy behind them"
++ When something gets played often, it receives a name for easier reference.
It is easier to say Marshall, than
1 e4 e5 2 Nf3 Nc6 3 Bb5 a6 4 Ba4 Nf6 5 O-O Be7 6 Re1 b5 7 Bb3 O-O 8 c3 d5, but it is the same.

"Is the decision to play a specific opening purely a matter of preference?" ++ Yes.

"Are Black's openings always based on White's opening?" ++ Yes

"Are some openings more aggressive than others?" ++ Yes

"If this is ultimately a decision of preference" ++ Yes

"do you recommend me to look for one that I like"
++ You need 3: in order of decreasing importance:
a defence for black against 1 e4, a defence for black against 1 d4, and an opening for white

"play only that one until I become more familiar with the game?"
++ Yes. By playing the same in every game you accumulate experience.

I got this,...

1) Is the decision to play a specific opening purely a matter of preference?

Yes. There are dozens (scores?) of fully playable openings. They go in and out of fashion. Chess Grandmasters are as fashion-conscious as teenage girls.

2) Are Black's openings always based on White's opening?

If you mean, "Can a Sicilian Defense only be played against White's 1. e4? Can a King's Indian Defense only be played against White's 1. d4?" then yes, White's initial move limits which defenses Black can choose to play.

This ignores the possibility of transpositions, which just refers to a player reaching a known position through an inversion of the usual move-order.

3) Are some openings more aggressive than others?

Yes. And correspondingly, some openings are more risky while offering more active play, while other openings are safer but more passive.

4) And this last question, the most important for me. If this is ultimately a decision of preference, do you recommend me to look for one that I like and play only that one until I become more familiar with the game?

Certainly, play the opening system or systems that interest you personally, not the ones that Grandmaster Egghead is playing.

As for playing only one system or several... it's a trade off. Playing a single system will enable you to know it better, and perhaps score somewhat better with it... but it will also mean that you are being exposed to only a limited set of all the possible patterns of play. This might slow your overall development as a player, because you end up facing similar problems in each game; instead of facing a wider array of decisions that will challenge you more and stretch your abilities as a player.

I always played a few different systems, not just one.