Actually use threading instead of single thread

Main.c

@@ -187,7 +187,7 @@ int main(int argc, char* argv[]) {
             // A connection has been established. Open new thread.
             char* ip = inet_ntoa(client_address->sin_addr);
             printf("Client IP: %s     Conn FD: %d\n", ip, *conn_fd);
-            pthread_create(&thread_array[0], &attr, serve_request, (void*) &((struct conn_obj) {copy_int(&index), conn_fd, client_address}));
+            pthread_create(&thread_array[index], &attr, serve_request, (void*) &((struct conn_obj) {copy_int(&index), conn_fd, client_address}));
         }
 
         // Check if any threads have finished. If so, join.