How to make multiple objects share same variable

I have multiple players that i want the enemies to attack. I tried using arrays and tags, but my case is different. My script depends on another scripts that makes the player take damage and the enemy treats that script as the player. Here is the script for the enemy that assigns the player to the enemy, this is the one in want to have multiple players in the SC_DamageReciever variable. I think arrays would work, but because of the references to the other script, tags could work.

 using UnityEngine;
 using UnityEngine.SceneManagement;
 
 public class SC_EnemySpawner : MonoBehaviour
 {
     public GameObject enemyPrefab;
 
     public SC_DamageReceiver Player;
  
     public Texture crosshairTexture;
     public float spawnInterval = 2; //Spawn new enemy each n seconds
     public int enemiesPerWave = 5; //How many enemies per wave
     public Transform[] spawnPoints;
 
     float nextSpawnTime = 0;
     int waveNumber = 1;
     bool waitingForWave = true;
     float newWaveTimer = 0;
     int enemiesToEliminate;
     //How many enemies we already eliminated in the current wave
     int enemiesEliminated = 0;
     int totalEnemiesSpawned = 0;
 
 
 
     // Start is called before the first frame update
     void Start()
     {
        
 
         //Wait 10 seconds for new wave to start
         newWaveTimer = 2;
         waitingForWave = true;
     }
 
     // Update is called once per frame
     void Update()
     {
         if (waitingForWave)
         {
             if (newWaveTimer >= 0)
             {
                 newWaveTimer -= Time.deltaTime;
             }
             else
             {
                 //Initialize new wave
                 enemiesToEliminate = waveNumber * enemiesPerWave;
                 enemiesEliminated = 0;
                 totalEnemiesSpawned = 0;
                 waitingForWave = false;
             }
         }
         else
         {
             if (Time.time > nextSpawnTime)
             {
                 nextSpawnTime = Time.time + spawnInterval;
 
                 //Spawn enemy 
                 if (totalEnemiesSpawned < enemiesToEliminate)
                 {
                     Transform randomPoint = spawnPoints[Random.Range(0, spawnPoints.Length - 1)];
 
                     GameObject enemy = Instantiate(enemyPrefab, randomPoint.position, Quaternion.identity);
                     SC_NPCEnemy npc = enemy.GetComponent<SC_NPCEnemy>();
                     npc.playerTransform = Player.transform;
                     npc.es = this;
                     totalEnemiesSpawned++;
                 }
             }
         }
 
         if (Player.playerHP <= 0)
         {
             if (Input.GetKeyDown(KeyCode.U))
             {
                 Scene scene = SceneManager.GetActiveScene();
                 SceneManager.LoadScene(scene.name);
             }
         }
     }
 
     void OnGUI()
     {
         GUI.Box(new Rect(10, Screen.height - 35, 100, 25), ((int)Player.playerHP).ToString() + " HP");
 
 
         if (Player.playerHP <= 0)
         {
             GUI.Box(new Rect(Screen.width / 2 - 75, Screen.height / 2 - 20, 150, 40), "Game Over\nPress 'U' to Restart");
         }
         else
         {
             GUI.DrawTexture(new Rect(Screen.width / 2 - 3, Screen.height / 2 - 3, 6, 6), crosshairTexture);
         }
 
         GUI.Box(new Rect(Screen.width / 2 - 50, 10, 100, 25), (enemiesToEliminate - enemiesEliminated).ToString());
 
         if (waitingForWave)
         {
             GUI.Box(new Rect(Screen.width / 2 - 125, Screen.height / 4 - 12, 250, 25), "Waiting for Wave " + waveNumber.ToString() + ". " + ((int)newWaveTimer).ToString() + " seconds left...");
         }
     }
 
     private void NewMethod()
     {
         GUI.Box(new Rect(Screen.width / 2 - 35, Screen.height - 35, 70, 25), Player.weaponManager.selectedWeapon.bulletsPerMagazine.ToString());
     }
 
     public void EnemyEliminated(SC_NPCEnemy enemy)
     {
         enemiesEliminated++;
 
         if (enemiesToEliminate - enemiesEliminated <= 0)
         {
             //Start next wave
             newWaveTimer = 2;
             waitingForWave = true;
             waveNumber++;
         }
     }
 }

this is the damage reciever

 using UnityEngine;
 
 public class SC_DamageReceiver : MonoBehaviour, IEntity
 {
     //This script will keep track of player HP
     public float playerHP = 100;
     public SC_CharacterController playerController;
     public SC_WeaponManager weaponManager;
 
     public void ApplyDamage(float points)
     {
         playerHP -= points;
 
         if (playerHP <= 0)
         {
             //Player is dead
             playerController.canMove = false;
             playerHP = 0;
         }
     }
 }
 

this is IEntity

 //Entity interafce
 interface IEntity
 {
     void ApplyDamage(float points);
 }

thanks in advance :)