[SalesForce] Is it possible to create the own Salesforce Trailhead Module

At the time I did it, I used this line of code and it worked. That's true it's not clear in the Trailhead module how to do it.

component.set("v.newItem", "{'sobjectType':'Camping_Item__c','Name':'',Quantity__c': 0,'Price__c': 0}");

I suspect problem is the endpoint URL. It appears you are using the Enterprise API based on the structure of the urn:sObjects xsi:type.

For the partner API I'm using the following. Note that this is what comes back in the loginResponse serverUrl:

https://curious-raccoon-253753-dev-ed.my.salesforce.com/services/Soap/u/36.0/00D7F0000000001

For the enterprise API you would need to swap out the /u/ for /c/. E.g.

https://curious-raccoon-253753-dev-ed.my.salesforce.com/services/Soap/c/36.0/00D7F000000001

Of course, your trailhead playground will have a different sub domain and trailling org id

I tried again to replicate your call to the Enterprise API via SOAP UI by copy an pasting your sample request and changing the sessionId. I tried both with and without the Org ID on the end of the URL. Works on my machine™

Does SOAP UI work against other orgs, or is it just your scratch org that is causing the connection refused error?

It really seems like a networking level error. I'd try using Soap UI from a different machine and/or another tool that uses the Soap API to update records. If your sole goal is to pass the Trailhead challenge you can probably trick the validation by using another API based tool to create the Account record.