When you are talking to a 3rd person, fundamentally
That is something that we all created together.
With regard to using them as first person, plural, possessive pronouns, this a nuanced choice.
I'm not asking about using them as subjects, objects, topical nouns, etc. Just as possessive pronouns.
My feeling is that #1 is about taking more direct credit for what was accomplished? It sounds rude? Like you considered yourself the lead in a small group of 4 or 5 people?
Even if you were the lead, always express to outsiders that a team of equals, among them yourself, accomplished something? That is choice #2?