The term 'true' rc is more commonly used when talking about the later/more recent players because of the introduction or parallels and alternate card types. For example, in 09/10 there would be dozens of RC's of James Harden, but the 'True' ones people refer to SHOULD be the first releases of him. The argument starts when it comes to different brands etc. For example, with Harden, the UD Draft Edition would be one of the first of him, however he wasn't in NBA uniform, so I would personally say the first would be the first in NBA uni. Even then, you have 09/10 UD first edition, 09/10 UD, 09/10 Topps and 09/10 Panini. The first release from each brand should be considered their 'true' rc and you can choose which you like better??
With the older players, there wasn't many, if any, card companies going around so the first that DID produce that player would be considered their RC
Looking at Jordan, he was drafted in 84, but they didn;t produce a card until 86/87 Fleer, so that is his RC, same with Ewing, he was drafted in 85, but again, 86/87 Fleer is his RC!
Here are some of the easier ones to identify (I think), the rest would be a matter of working out all of the NON PARALLEL/GU/AUTO cards and finding out which was released first!
Patrick Ewing - 86/87 Fleer #32
Walt Frazier - 69/70 Topps #98
Shaq - 92/93 Fleer #401
LeBron James -
Kobe Bryant -
Dennis Rodman - 88/89 Fleer #43
Carmelo Anthony -
Magic Johnson - I think his first RC was a triple with Bird and Erving???