Low level + Backstory = Used to scale your actual tangible power and skillset. It does not prevent you from having diverse skills or experiences but you cannot be a level 1 character that is a veteran of many wars and a champion of the army as a level one because that is not how the system works. In your backstory you are this great epic warrior but in actual combat you are barely more competent than a farmer. This is not a matter of your perception or opinion it is an objective fact and how the system balance was created. This does not affect your age either. It directly affects the numerical values of your skills.
Not true. Your backstory can be anything you like. Of course you can be a veteran warrior, many characters start their Fighters off in just such a way.
You are confusing XP and game experience with the character backstory. One is a mechanism used within the game, the other is story-telling technique to explaining why your character is where he or she is now. Just because a PC is not high level, does not mean that the campaign, group, rules and GM cannot recognise that they are highly experienced.
To quote about age:
AGE
The age entry notes the age when a member of the race is considered an adult, as well as the race’s expected lifespan. This information can help you decide how old your character is at the start of the game. You can choose any age for your character, which could provide an explanation for some of your ability scores. For example, if you play a young or very old character, your age could explain a particularly low Strength or Constitution score, while advanced age could account for a high Intelligence or Wisdom.To quote from the section on Backgrounds:
Your character’s background reveals where you came from, how you became an adventurer, and your place in the world. Your fighter might have been a courageous knight or a grizzled soldier. Your wizard could have been a sage or an artisan. Your rogue might have gotten by as a guild thief or commanded audiences as a jester.Those pieces of advice on creating your character strongly suggest that you can start a character as someone who has seen a bit of life before becoming an adventurer. A 'grizzled fighter' is not some fresh-faced newcomer, and neither is a sage a newly apprenticed wizard.
