Then I thought about 'Sick' teaser and tried to guess what each member represent.

So the elevator represent 'BTS' as a group and an army(a real army, not fans) 

(Note: might be confusing while reading)

RapMon was the first member to be revealed. ARMYs know that BTS exist because Bang-PD wanted to create a group for RM, thus BangTanSoNyeonDan was created. RM dressed up as a military soldier(there's a name for it but I forgot), it represent that soldiers are needed for army because it is not if there wasn't any soldiers to work in the army.

Next was Suga. Suga joined the current line-up as a pilot(I think cause there's a white undershirt under the navy jacket). Suga is a composer at heart, rapping was just an addition for its composing, but he had to become a rapper to be able stay in the group. He is still composing while living as an artist. An army don't really need a pilot, but it's a great advantage on their side. So Suga as a pilot shows that a member that could compose and this make the group advantageous than other group while still completing the 'idol' look.

J-Hope is a biker(not sure, many are confused what he is). Bikers are really active, however they are not really beneficial. J-Hope as a dancer is not that important to a used-to-be hiphop group. But overtime, the hiphop group changed to an idol group, where dance could really come in handy. Bikers are more faster than cars and able to cut through car jams, there are much more easier delivering infos in a pinch. So in the end, they are quite useful despite not really in contact with the army. (Okay, the last 2 sentences I just made up cause Idk what to put. My other thought would be how bikers know how to control weapon more easier since motorbikes are really hard to ride)

Jin came into the army as a doctor. Jin is known as the 'underappreciated member', always at the back and his dance, vocal and rapping are average. However, he's appointed as the visual and we all know that Kpop Groups are mainly looks(don't deny it), so he could help a bit on that. Jin is also the mother of the group, taking care of the members, making sure they are healthy to do their work. I'm sure this is self-explainatory, doctors are needed in armies when the soldier got injured and making sure they are able to fight at war. 

Jungkook dressed up as a police officer. 'Golden Maknae' is the nickname given to Jungkook. He's talented in every aspect the group need, rap, dance, vocal and even looks. Other factor can also lead to his nickname such as an advantage of young age. Policemen (for me) are almost similar to soldiers, only policemen work in the people while soldiers are at the battle field. Police can do things soldiers need, only average such as protecting, using weapons, give out instructions/commands. Policemen can be promoted as soldiers(I think) and Jungkook here represent that he's still young but continuing to grow and work hard to be a soldier like RapMon or Suga.

V and Jimin here will a bit confusing, so bare with me.

V is a detective. V is nicknamed as 'Alien' which is a being outside the world(duh). When he came into group, he was quite not fitting in the group, he's a farm boy that grew in the village but he was chosen because of his looks. V learned how to fit inside the group perfectly, just like how aliens tries to fit into the human world (lol). Detective are not important in the army just like the biker, but detective could help the army at least by investigating their opposing army in battle, like a spy, I guess...so the army could adapt the detective even if it didn't fit in the army.

Jimin was the last one to join. He is also the last one to join the group. Jimin dressed up as a normal worker, with his papers. Jimin is just an average trainee, with enough practice, he possibly could debut, but practice isn't the only thing that make people debut. Hardwork is needed, to show that he deserve to debut, he deserve to shine, he deserve all those training. Thus, in the teaser pic, he was the only one shown to be doing work, to show that goodlooking and job(talent) isn't the only thing that could make the dream work. I'm not saying that the others don't work hard enough, everyone work hard to deserve in the 'elevator', its just the others had jobs that could easily make them into the group(army) while Jimin was just an ordinary worker. He work extra hard, just to fit into the group(army).

Finally, when Jimin joined the elevator(BTS), everyone looked up. This shows that the elevator(BTS) ready to go up, ready to debut. The elevator is small, but it's big enough for all the members to fit, if there's another member, it won't fit. BTS is already perfect and enough just to debut, no more no less. The numbers the members press are (maybe) that how many members bts had when they joined(including themself) and in the end, Jimin pressed '7', the amount of members in total as he joins. When the elevator moves up, BTS 'rise' in the kpop industry, the top is their goal. But elevators sometimes stop, indicating that they have to be patience and remember that it isn't that easy(fast) to reach their goal. 

That's all, I guess...I was bored and I had spent 2 hours writing this (totally worth it!). I somehow wanted to add ARMYs here but maybe another time. Re-reading this is quite confusing, sorry orz my english had went to space while writing these @.@