the first sex is not that important.
more precisely, it's important not for the reasons it's usually discussed.

age is important only if you were a child and then you matured so fast.
place is important only if it was a public humiliation that made you feel guilty about your body.
person is important only if they turned into your nightmare who smiled in response to your tears.

the first sex is not that important.
perhaps the only thing that matters is how many times it will happen again.

sometimes it determines a lot:
whether you will dream of being harassed in search of approval.
whether you will murmur «slut» while touching yourself in the bathroom.
whether you will beg your partner to slap you in the face because you only deserve it.
whether you will equate sex with violence and deny its existence in love.
whether you will look for him in strangers and expect them to grab your hand and not let go.
whether you will consider nudity dangerous, and any approach to your body is practically lethal.

so the first sex is not that important.
only if it peels off your skin with your clothes and underwear.