Before starting, ensure you have Python installed on your system as well as the necessary libraries. Use pip to install the required packages:
```bash
pip install requests pika
```
`requests` will be used to interact with the Pexels API, and `pika` is a pure-Python RabbitMQ client library.

You need an API key to access Pexels. Create an account on Pexels, navigate to the API section, and generate your API key. Store this key securely as you will use it to authenticate your requests.

Write a Python script to make GET requests to the Pexels API. Use the requests library to handle these requests and pass your API key in the headers. For example, to fetch popular photos:
```python
import requests

API_KEY = 'your_pexels_api_key'
headers = {
'Authorization': API_KEY
}
response = requests.get('https://api.pexels.com/v1/curated', headers=headers)

if response.status_code == 200:
data = response.json()
else:
print("Failed to fetch data:", response.status_code)
```

Install RabbitMQ on your local machine or server. Follow the RabbitMQ installation guide for your operating system. Once installed, start the RabbitMQ service. You can use the default guest credentials for a local setup, but it's recommended to set up a dedicated user for production use.

Use the pika library to establish a connection with your RabbitMQ server. Create a connection and a channel, then declare a queue where you'll send the data from Pexels:
```python
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
channel = connection.channel()
channel.queue_declare(queue='pexels_data')
```

Once you've fetched the data from Pexels, convert it to a suitable format (e.g., JSON string) and publish it to the RabbitMQ queue. Use the `basic_publish` method to send data to the declared queue:
```python
import json

for photo in data['photos']:
message = json.dumps(photo)
channel.basic_publish(exchange='', routing_key='pexels_data', body=message)
```
This loop iterates over each photo in the data and sends it to the queue.

To verify the data is being sent correctly, write a consumer script that listens to the queue and processes the data. Use the pika library to consume messages:
```python
def callback(ch, method, properties, body):
print("Received %r" % body)

channel.basic_consume(queue='pexels_data', on_message_callback=callback, auto_ack=True)
print('Waiting for messages. To exit press CTRL+C')
channel.start_consuming()
```
This script will output each message received from the queue, confirming that your data flow from Pexels to RabbitMQ is functioning correctly.

This guide provides a foundational approach to moving data from the Pexels API to RabbitMQ using pure Python libraries without any third-party connectors or integrations. Adjust and expand on each step as necessary to fit your specific use case and environment.