Since 4e level 1 doesnt really happen until 5e level 5, it seems worthwhile to split up the concept of ‘class’ into separate tiers. In other words, a ‘class’ includes impactful choices, at different tiers. At level 1, the player chooses a Student Course. At level 5, the player chooses a Heroic Profession. At level 13, the player chooses a Paragon Path. At level 21, the player chooses an Epic Destiny.
This means the Student tier is more like level zero. Low level Courses include basic fighting skills, basic stealth skills, basic casting skills, or so on. For example, Cleric is a Profession that begins at level 5. The Cleric player might have chosen a Course that relates moreso to spellcasting, such as a Healer (thus comes with extra magical abilities), while an other Cleric player might have chosen a Course that relates moreso to fighting (thus sports heavy armor and a special weapon). Both Clerics, regardless of earlier Student tier choices, would progress according to the Cleric Profession, from levels 5 to 12.
At level 13, the Cleric chooses one from a number of Paths.
At level 21, the player picks one from a number of Destinies.
A core ‘base’ class comes with an advancement track, that includes a default Course, Profession, Path, and Destiny. But a player can mix-and-match these according to taste.
4e style works well with the above approach from level 5 and up. Likewise level 0 flavors, such as Harry Potter wizard students or the kid longing to be a knight, get handled at levels 1 to 4.
A Wizard might well come from a Student Course that specializes in swordfighting, and really only begins spellcasting at level 5.
Student Tier
• Course (levels 1 to 4)
Heroic Tier
• Profession (levels 5 to 12)
Paragon Tier
• Path (levels 13 to 20)
Epic Tier
• Destiny (levels 21 to 24)