PHP　二次元配列のこと

<?php
  // 2次元配列を作成する
   $player = "忍者";
   $teamA = [$player, "戦士", "魔法使い"];
   echo $teamA[0] . ",";
   echo $teamA[1] . ",";
   echo $teamA[2] . "\n";
 
   $teamB = [$teamA[0], $teamA[1], $teamA[2]];
   echo $teamB[0] . ",";
   echo $teamB[1] . ",";
   echo $teamB[2] . "\n";
 
   $teamC = ["勇者", "戦士", "魔法使い"];
   $teamD = ["盗賊", "忍者", "商人"];
   $teamE = ["スライム", "ドラゴン", "魔王"];
   $teamS = [$teamC, $teamD, $teamE];
   print_r($teamS);
   echo $teamS[0][0] . ",";//$teamS[0]：$teamSの最初のインデックス"$teamC"　$teamS[0]：$teamCの"勇者"
   echo $teamS[0][1] . ",";//$teamS[0]：$teamSの最初のインデックス"$teamC"　$teamS[0]：$teamCの"戦士"
   echo $teamS[0][2] . "\n";//$teamS[0]：$teamSの最初のインデックス"$teamC"　$teamS[0]：$teamCの"魔法使い"
?>

<?php
  $teamS[0][0] = "狙撃手"; // $teamCの値が勇者→狙撃手に変更された
?>