Why is e5 the strongest move here for white? [FEN &quot;rnb1kb1r/pp1pp2p/2p2ppn/q7/2BPP3/5N1P/PPPN1PP1/R1BQ1RK1 w kq - 3 8&quot;]

I'm a noob at chess, as I just started playing a week back. I played
as White here, and Stockfish recommended e5 as the next move. I understand the correct move for Black would be f5 after I play e5, but just in case black plays fxe5, I'd have to take that pawn with dxe5. So Black lost a side pawn in exchange for my center pawn and my pawn on d4 got stuck alone on e5 and will be easier to kill rather than a pawn chain. What am I missing here in this move being the strongest move at this position? It cannot be queened since d6/d7 is coming. What does this do apart from just threatening the Black pawn, from going d6/d7, and breaking black into 2 pawn islands?
You've given some good, very long-term reasons not to play e5. But in this position, dynamic considerations outweigh these long-term reasons.
Look again at the position: you have developed (if you have not encountered this term before, it means moving your pieces from their starting squares so they can participate in the game) two knights, a bishop, and castled. Your opponent has developed a queen and a knight, and hasn't castled. In other words, you are well ahead in development. It's for this reason Stockfish already says your position is very strong - SF 11 is giving +3 eval at depth 22.
A lead in development is usually a signal to attack - you have more pieces that can attack than your opponent can defend. Therefore you want to attack in this position. You want open lines so your major pieces can infiltrate, and you definitely want to do this before your opponent completes their development and castles. e5 does that. Follow what Stockfish gives as the principal variation after e5.
[fen &quot;rnb1kb1r/pp1pp2p/2p2ppn/q7/2BPP3/5N1P/PPPN1PP1/R1BQ1RK1 w kq - 3 8&quot;]

1. e5 f5 {You also mention 1...fxe5, but this move would be even worse since after 2.dxe5 White can now play Ne4-d6+. If Black plays ...exd6 then the King would be on an open file and perish quickly, but if Black plays ...Kd8, Bxh6 followed by Nf7+ still wins material. Stockfish even wants to play 2.b4 Qxb4 3. Rb1, sacrificing a pawn to develop even faster, illustrating how much attacking potential White has.} 2. Bb3 {Threatening Nc4-d6 with the same plan as the analysis in the previous move. Note White can also play on the kingside with Ng5 or in the center with Re1 intending e6.} Nf7 3. Nc4 Qd8 {&quot;Undeveloping&quot; the Queen. Black could play ...Qc7 but at this point Black needs first and foremost to guard against White's attack. Still, having to undevelop the Queen shows just how awful Black's position is.} 4. Ng5 {Knight's defended by the c1-Bishop.} e6 {Or what? White threatens Nc4-d6+. If Black plays ...Nxd6, then exd6 would threaten both Bf7# and Nf7 winning material. 4...Nxg5? Bxg5 simply threatens Nd6+ winning the Queen, and 5...Bg7 6. Nd6+ Kf8 7. Nf7 still wins material. Black has to block the a2-g8 diagonal.} 5. Nxf7 Kxf7

Black's kingside looks like Swiss cheese and White has many promising ideas such as Nd6+ (effectively forces Bxd6) followed by Bh6, Qf3 intending g4 to pry open Black's pawn shield, etc. Either way, White is attacking, and the position is one where long-term pawn structure is not important.