The information in these pages is generally intended as a reference guide for GMs. A GM can provide information from these pages that their player(s) should know about and can find information in these pages to give as answers to knowledge rolls. It is recommended that a GM running a game in this setting to at least skim through the lore and other setting pages before running a game. Improvising and creating your own take on the game's universe is of course up to the GM's discretion.
Remember: running a game that is fun for you and your players is the most important thing. If you think any changes (in the lore or in the rules) would make the game better for your group, always do it.