Will Serial.read() read what is written by Serial.print() in one same sketch?

I have an Arduino sketch that is intended to do many things: Read from a DHT11 (temp & humidity) sensor, a KY-026 (infrared) sensor - ALL GOOD - but is also intended to read Serial responses written by an external programming language through a COM port. This last part worked well separately, before trying to combine everything in one sketch.

I have not further tested, but I believe that command Serial.read() takes the values written by both sensors with the command Serial.print(), instead of taking the values from COM port.

I attach my code:

#include <dht11.h>
#define DHT11PIN 4

int led = 13; // define the LED pin
int analogPin = A0; // KY-026 analog interface
int analogVal; //analog readings
dht11 DHT11;

void setup()
{
  pinMode(led, OUTPUT);
  pinMode(analogPin,  INPUT);
  Serial.begin(9600);
  pinMode(12, OUTPUT);
}

void loop()
{

  int incomingByte;
//*********** LIGHT LED ON-OFF FROM COM PORT***********//

  if (Serial.available() > 0) {
    // read the incoming byte:
   incomingByte = Serial.read();
  
  }

   if(incomingByte = 0x01){
    digitalWrite(12, HIGH);
    
  }
   else if(incomingByte = 0x00){
       digitalWrite(12, LOW);
   }
//*********** LIGHT LED ON-OFF FROM COM PORT ***********//
  
//*********** DHT-11 ***********//
  int chk = DHT11.read(DHT11PIN);
  Serial.print("-");
  Serial.print("H");
  Serial.print((float)DHT11.humidity, 2);
Serial.print("-");
  Serial.print("T");
  Serial.print((float)DHT11.temperature, 2);
Serial.print("-");
  delay(1000);

  //*********** DHT-11 ***********//

//*********** KY-026 ***********//
  
  // Read the digital interface
   analogVal = analogRead(analogPin); 
  if(analogVal <= 30) // if flame is detected
  {
    digitalWrite(led, HIGH); // turn ON Arduino's LED
  }
  else
  {
    digitalWrite(led, LOW); // turn OFF Arduino's LED
  }

  // Read the analog interface
  analogVal = analogRead(analogPin); 
  Serial.print("-");
  Serial.print("F");
  Serial.print(analogVal);// print analog value to serial

  delay(1000);
  //*********** KY-026 ***********//
}

What do you think of this?

Any comments will be much appreciated!

Which Arduino? What Serial.read()? What wiring? What evidence that there is a problem?

It is an Arduino Uno, with a led connected to pin 12 and another to GND.
So, does your question mean that we can read and write to serial with no problem of interference?

Your LED should be in series with a resistor unless there is a satisfactory one internally.

Serial reads and writes should not interfere with each other and have not interfered with each other for me.