I don't view the high / low gap as a large issue, myself. When I started playing, I looked at high level characters as goals to aspire towards, and have been told the same is the case now. Taking that away, and having the playerbase be largely one lump of "Well, I guess we're all the same" would take away a large piece of Alliance's flavor.
Quoted for emphasis.
I am at a lost at how big the biggest level currently is in Alliance I am under the impression it is very large
I don't think there's anything you can really do about the level gap. It simply is what it is and it's up to Plot teams and Players to make New Players feel welcome and useful.
To give you an idea of the level gap, and to illustrate my point about the importance of the Community as a whole: When I was Head of Plot for Alliance Oregon (2011-2015), in many of our events we would have both Level 1 and Level 2 characters at the low end, and at the high end we had a character that was above level 50, a few that were above level 40, and everything else in between. My plot team and I purposefully created content for 3 basic level ranges: Low (levels 1-10), Mid (20-25), and High (Level 35 and higher). You'll note that there are some levels missing in between those ranges, but those levels could easily go up or down depending on player experience, magic item ownership, and player skill.
We also had content every single weekend event for players of all ranges to participate in, this took the form of the Weekend Plot, so that visitors, new players, and players who hadn't been to the chapter in a while could jump right into relevant and important plot/story without having to know what was going on in the overarching story. I got The Weekend Story idea and its purpose from the Head of Plot I worked under from 2010-2011,
@jpariury . It was extra work for the team, a lot of extra work in some cases, but ultimately I felt it was an important thing to continue to make the game as accessible to as many players as possible. It has the added benefit of getting NPC's involved too! NPC's really like knowing what is going on and being involved with the story, and when they know the Weekend Story and they know they have an impact on it and can help tell that story, they are more likely to have fun and more likely to come back and NPC again.
Additionally, how effective a Character is, how effective a Player feels, is utterly and entirely up to the Plot team and how an event, module, town fight, or encounter is scaled.
All the rules in the world won't make up for bad scaling. And you can have as many rules and regulations as you want to attempt to help new players get involved, but those rules are useless if your Plot and Chapter Community (players and NPC's) aren't also there to do their part.