I'm fairly new to D&D 5e, but a pretty quick study (thanks at least in part to this site!) I'll be DMing a one shot game at a family event in a couple of months. One of my players has played a similar RPG system before, but is ... loose on rules in general. The rest are complete newbies, and some of them mostly want to play as a way to connect with the one who's played something else before (and is keen as a bean) rather than from their own internal initial interest. Obviously I want everyone to have a good time.
My initial thought was to run Lost Mine of Phandelver (the Starter Set campaign) seeing as I have it already, and it would give those less invested players pre-made characters if they don't want to roll their own from scratch. The problem is that it's designed to get them from 1st-5th level, and I'm not sure I want to play a game that lasts too many sessions.
After briefly considering homebrewing a one-shot (I really don't have time) I looked to see if there were any prewritten ones. (It turns out that there - are - LOTS). Many of them say they're for 3rd- to 5th-level (or some other combo) characters.
I feel like I'd like to start with the level 1 simplicity for my new players (though leveling in the game might be cool).
Does this mean that I'm limited to one-shots designed for level 1 characters, or is there an easy way to get a party of 4 or so level 1 characters through a game designed for level 3-4s?
If you feel that first-time players might do better with higher-level characters, feel free to include that in the rest of your answer.
Also, if the game goes a little long, and we need to have a second session to tie it off, that's probably fine. If it's likely to take much longer than about 6-8 hours, I doubt we'll get through it.