Answer:
How: It will have a very different chemical composition.
Why: Because the interstellar medium at the beginning of universe were compounded only of Hydrogen and Helium.
Explanation:
Once the Big Bang passed and the universe began its expansion, the temperature started to decrease, what allowed the combination of hydrogen and helium. Therefore, the chemical composition of the molecular cloud in which the first stars were formed only held those elements.
If the Sun and the solar system were formed from a molecular cloud with that composition, it will both have an absence of metallic elements (elements heavier than helium), since all of them are formed through nuclear reactions in the core of the stars, and each time a star dies, the interstellar medium for the next generation is enriched.
Key elements for life as Carbon, Nitrogen, Oxygen, Phosphorus and Sulfur will be missing for that hypothetical scenario.
For example, the lack of O3 (ozone) in the atmosphere of earth will allow that ultraviolet light hits the earth surface.
