Select the oldest from join - mysql

Question

I'm making my own archive system. Here is how it looks so far. I have following SQL tables:
CREATE TABLE items (
id int NOT NULL AUTO_INCREMENT,
serial_number varchar(255) NOT NULL,
catalog_number varchar(255) NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE entities (
id int NOT NULL AUTO_INCREMENT,
table_name varchar(255) NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE entities_relations (
id int NOT NULL AUTO_INCREMENT,
table_name varchar(255) NOT NULL,
entity_id int NOT NULL,
row_id int NOT NULL,
PRIMARY KEY (id)
);
Each entity where table_name is "items" has at least one item matched via entities_relations. entities_relations shows how many relations are between one entity and items. After saving an item it saves a new Item which is a copy of the previous one and adds a relation. Copies (archive items) don't create a new entity, they create only relation. The oldest relation is the original item.
The following SQL syntax shows me items list. It's wrong because it shows me all items, even if they are archived. I would like to display only the original ones. How can I change it to be able to display only original ones and ignore archives?
SELECT
items.*,
FROM
items
LEFT JOIN entities_relations ON
entities_relations.row_id = items.id
LEFT JOIN entities ON
entities.id = entities_relations.entity_id
WHERE
entities.name = 'items'
ORDER BY
entities.id DESC,
entities_relations.entity_id DESC
LIMIT 0, 50